Memory leak fix & added test.

build.gradle

@@ -110,7 +110,7 @@ buildscript {
     ext.jsr305_version = constants.getProperty("jsr305Version")
     ext.shiro_version = '1.10.0'
     ext.artifactory_plugin_version = constants.getProperty('artifactoryPluginVersion')
-    ext.hikari_version = '3.3.1'
+    ext.hikari_version = '4.0.3'
     ext.liquibase_version = '3.6.3'
     ext.artifactory_contextUrl = 'https://software.r3.com/artifactory'
     ext.publicArtifactURL = 'https://download.corda.net/maven'

node/src/test/kotlin/net/corda/node/migration/MemoryLeakTest.kt

@@ -0,0 +1,39 @@
+package net.corda.node.migration
+
+import net.corda.testing.core.ALICE_NAME
+import net.corda.testing.node.MockNetwork
+import net.corda.testing.node.MockNetworkParameters
+import net.corda.testing.node.internal.cordappsForPackages
+import org.apache.commons.lang3.SystemUtils
+import org.hibernate.internal.SessionFactoryRegistry
+import org.junit.Assume
+import org.junit.Test
+import kotlin.test.assertFalse
+
+class MemoryLeakTest {
+    @Test(timeout=300_000)
+    fun `memory leak test`() {
+        assertFalse(SessionFactoryRegistry.INSTANCE.hasRegistrations())
+        repeat(1) {
+            // Start mock network
+            Assume.assumeTrue(!SystemUtils.IS_JAVA_11)
+            val mockNetwork = MockNetwork(
+                    MockNetworkParameters(
+                            cordappsForAllNodes = cordappsForPackages(
+                                    listOf(
+                                            "net.corda.node.services.vault"
+                                    )
+                            )
+                    )
+            ).also { mockNetwork ->
+                mockNetwork.createPartyNode(ALICE_NAME)
+            }
+
+            // Stop mock network
+            mockNetwork?.stopNodes()
+            // mockNetwork = null
+        }
+        assertFalse(SessionFactoryRegistry.INSTANCE.hasRegistrations())
+    }
+}
+

testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/InternalMockNetwork.kt

@@ -73,6 +73,7 @@ import net.corda.testing.node.MockServices.Companion.makeTestDataSourcePropertie
 import net.corda.testing.node.TestClock
 import org.apache.activemq.artemis.utils.ReusableLatch
 import org.apache.sshd.common.util.security.SecurityUtils
+import org.hibernate.internal.SessionFactoryRegistry
 import rx.Observable
 import rx.Scheduler
 import rx.internal.schedulers.CachedThreadScheduler
@@ -621,6 +622,7 @@ open class InternalMockNetwork(cordappPackages: List<String> = emptyList(),
             }
             messagingNetwork.stop()
         }
+        SessionFactoryRegistry.INSTANCE.clearRegistrations()
     }
 
     /** Block until all scheduled activity, active flows and network activity has ceased. */